Modern injection systems for internal combustion engines increasingly feature piezo actuators for mechanical activation of the injectors, which exhibit better dynamic behavior when compared with conventional electromagnetic actuators. These types of piezo actuator conventionally have a piezo stack, in which a plurality of layered piezo elements are arranged one above the other, with layered electrodes being located between the individual piezo elements in each case. The electrical contacting of the piezo stack is undertaken by metallization strips which are arranged on opposite side surfaces of the piezo stack and extend over the entire length of the piezo stack, with the individual layered electrodes of the piezo stack being alternately connected to one of the two metallization strips. The two metallization strips are connected in their turn with two terminal posts which are arranged on opposite sides of the piezo stack and protrude from the end face of the piezo actuator to allow electrical contacting on the outside.
The use of a contact mat in the form of a wire mesh is known from DE 100 26 635 A1 for electrical connection of the metallization strips of the piezo stack with the associated terminal posts, with the contact mat featuring what is known as weft and warp threads. The weft threads are arranged in parallel to each other in this case, consist of a conductive material and connect the metallization strips of the piezo stack with the associated terminal post in each case. The warp threads on the other hand run at right angles within the contact mat to the weft and connect these to each other in order to mechanically stabilize the warp.
The disadvantage of this known contact mat is the fact that the operation of the piezo actuator can result in breaks and tears in the contact mat.